US 4,527,137 AGranted

Evanescent resonator frequency multiplier

AssigneeThe United States of America as represented by the Secretary of the Army

InventorJoseph H. Hartley

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Abstract

A frequency multiplier for electromagnetic waves in which multiples of the input frequency propagate, while the input frequency evanesces. A rectangular waveguide or other suitable wave conveying element with a cut-off frequency above the input frequency but below the output frequency contains the multiplying structure. The input frequency is multiplied using a post located in the waveguide or other element adjacent to the source of input waves. The post may define a multiplier gap between one of its surfaces and a wall of the waveguide or other element, in which case the multiplier gap may contain a multipactor between its surfaces which generates multiples of the input frequency. The multiplier gap may alternatively contain a non-linear element responsive to a high electric field, such as a ferroelectric material, which also generates multiples of the input frequency. Alternatively, the post may be surrounded by a non-linear element of ferromagnetic material responsive to a strong magnetic field. In either embodiment, waves at the same frequency as the input waves cannot propagate, but waves above the cut-off frequency propagate through the waveguide or other element to an output aperture.

Claims18

Dependent claims

A frequency multiplier for electromagnetic waves, comprising:

a metallic waveguide in which electromagnetic waves propagate at or above a cut-off frequency and in which electromagnetic waves below the cut-off frequency cannot propagate, the waveguide having a first output aperture at one end for coupling out electromagnetic waves therefrom;
an input aperture in a side wall of said waveguide;
a source for introducing input waves at a predetermined input frequency below the cut-off frequency through said input aperture into the waveguide;
and
a conductive post positioned on an inner wall and extending transversely toward the opposite wall of said waveguide to provide a predetermined narrow gap therebetween, the dimensions of said gap and post and waveguide determining said input frequency, said post being positioned at a location spaced longitudinally from the output aperture and laterally from the input aperture and including a coating of multiplier material disposed on a surface of said post providing a non-linear response for receiving said input frequency waves from said source and for generating waves at a predetermined output frequency greater than the cut-off frequency, said narrow gap between said post and opposite wall being empty except for any portion occupied by said multiplier material.

2 more elements

Dependencies are inferred from the claim text.